Flooding Factors Experiment

Environmental Geology, GLG110, Fall 2006

Due Tuesday, November 7^th

Purpose: to test how certain earth materials respond to water infiltration and saturation.

Materials:

• Three plastic cups
• Tap water
• Second and minute timer
• Gravel (>2mm), sand (<2mm), and dirt (~50% organic material mixed with ~50% sand or mud).
• A relatively dry lawn with grass vegetation

Tasks:

1. Read the steps below before performing.
2. Obtain three clear plastic cups from your professor. The volume of this cup is ______ milliliters.
3. Use and ice pick type tool and make 10 holes in the bottom of the cup, each hole being about 1/8^th inch in diameter.
4. Fill your cup with one of the three materials (gravel, sand, and dirt) to about half full. Do gravel first, sand second, and the dirt sample last for the following steps.
5. Compact the sediment with your fingers until you cannot compact it anymore. This represents natural compaction of sediment on natural surfaces.
6. Fill the other cup half full with normal cold temperature tap water (most rain water is cold or colder than this since we’re representing rain water conditions).
7. With timer ready, and your third cup underneath the cup with the sediment, pour the water into the other cup, but not so fast that it erodes a hole in the top of your sediment.
8. Measure how long it takes for the water to stop draining into the top of the sediment. This is the time it took your volume of water to enter the sediment.
9. When the water has finished draining the sediment cup, note how much water (in milliliters) was left in the bottom cup, and measure the difference of the water that remained behind in the sediment.
10. Keep your records in the table below.
11. Now, perform the same experiment again, this time the sediment is wetted, but not completely saturated. Calculate the infiltration rate for this second experiment on the same type of sediment.
12. Redo the previous steps for the other two materials and complete you table below.
13. For the yard sample with vegetation (grass would be nominal), you do not want to disturb the yard sediment, so you will take your empty cup, the one with the holes in it, and place it firmly (right side up) on the ground in contact with the top of the yard surface or ground. You may have to “shave” the grass off in order to get a good contact.
14. Pour water into the cup, a full cup would give a more accurate reading, and measure the time it takes to infiltrate your volume of water into the yard. Record your results and perform a second time after you ‘think’ the water has percolated down far enough so that the sediment is not completely saturated with the first experiments water.

Record your results in the table below and bring to class on Tuesday.

Name __________________ Date _________

Data Table for Infiltration Rates in Different Sediments

Type of Material	Infiltration Rate through dry material (milliliters per second)	Infiltration Rate through already wetted material (milliliters per second)
Gravel
Sand
Dirt/Sand Mix
Yard with Vegetation

List and state one hypothesis before performing one experiment:

Explain the difference, if any, between your hypothesis and the results:

What did you like about this experiment?

Where there any difficulties while performing this experiment?